1. Field of the Invention
The present invention relates to a hybrid system control apparatus and a hybrid system control method.
2. Description of the Related Art
A hybrid system provided with an engine and an electric motor is known in which a hybrid vehicle is driven by a power produced by at least one of the engine and the electric motor. In the hybrid system, in addition to an engine system, an electric motor system, which is formed by, for example, an electric motor, a generator, an inverter, a transmission, or the like. Therefore, in the hybrid system, each of the systems may be provided with a cooling system that performs heat exchange with an exterior.
Further, if the engine in the hybrid system has a forced air induction device, an intercooler that cools boost air (intake air) from the forced air induction device is usually provided. The forced air induction device increases the temperature of the boost air to, for example, 200° C., by boosting the pressure (compression). If the engine inhales the high temperature boost air, charging efficiency (volumetric efficiency) is reduced. Therefore, the boost air is cooled by radiating heat of the boost air from the intercooler.
Japanese Patent Application Publication No. 2006-144703 (JP-A-2006-144703) describes a hybrid vehicle driven by at least one of an internal combustion engine having a forced air induction device and an intercooler, and an electric motor. The hybrid vehicle is provided with an internal combustion engine cooling system having an internal combustion engine radiator, and an inverter cooling system having an inverter radiator. In the hybrid vehicle described in JP-A-2006-144703, the inverter radiator, the intercooler and the internal combustion engine radiator are disposed in this order from the front of the vehicle.
Drive elements (for example, electric motor, generator, transmission, etc.) that form an electric motor are lubricated by lubricant. At the time of cold start of the hybrid system, the viscosity of lubricant in the electric motor system is high. Therefore, when the vehicle is driven by the power output from the electric motor, friction loss increases. Because the increase in the friction loss deteriorates fuel economy, the electric motor system must be warmed up quickly at the time of cool start.
However, in the hybrid vehicle described in JP-A-2006-144703, because the inverter radiator and the intercooler are disposed in this order from the front of the vehicle, the intercooler radiates heat of the boost air whose temperature is increased by the compression in the forced air induction device, and the ambient air heated by the heat radiation flows toward the rear side of the vehicle due to the traveling wind (wind flowing from the front to the rear of the vehicle while the vehicle is moving forward) without passing by the inverter radiator.
Accordingly, at the time of cold start of the hybrid system, it is sometimes difficult to warm up the electric motor system quickly. In other words, it is difficult to reduce the friction loss of the electric motor system quickly at the time of cold start, and the fuel economy may be deteriorated.